1. Field of the Invention
The present invention relates to a system and a method for switching multicast data in an Ethernet network, and more particularly, to a system and a method for simultaneously providing a layer-2 multicast switching function and a layer-3 multicast routing function on the basis of a virtual interface.
2. Description of the Related Art
A recent network equipment based on an Ethernet constituting the Internet is roughly classified into a switch performing a switching function of a 2 layer and a router performing a routing function of a 3 layer.
The Ethernet-based 2 layer multicast switching function conforms to Institute of Electrical and Electronics Engineers (IEEE) 802.1D and 802.1Q. In operation, a multicast Ethernet frame in an Ethernet network is a frame where a lowermost bit of an uppermost byte of a 6-byte destination media access control (MAC) address is set to 1, that is, a first byte is displayed as 0x01.
Also, a frame of the multicast Ethernet frames where upper 3 bytes of a 6-byte destination media access control (MAC) address are displayed as 0x01, 0x80, and 0xC2 is a bridge protocol data unit (BPDU) frame, and is used for delivering a control message between switches, and should not be forwarded but transmitted to a controller for processing. On the other hand, a frame of the multicast Ethernet frames where upper 3 bytes of a 6-byte destination MAC address are displayed as 0x01, 0x00, and 0x5E is an Ethernet frame for multicast data. When a corresponding switch provides a layer-2 multicast table, the Ethernet frame for the multicast data is delivered to only a corresponding output port. However, when the corresponding switch does not provide a separate layer-2 multicast table, the Ethernet frame for the multicast data is forwarded to all output ports. Of course, when the corresponding switch provides a virtual local area network (VLAN) function, the Ethernet frame is forwarded to only a VLAN member port.
On the other hand, an Ethernet-based layer-3 multicast routing function conforms Internet Engineering Task Force (IETF) standards. In operation, a layer-3 multicast routing function in a router system uses multicast routing protocols such as Internet Group Management Protocol (IGMP), Protocol Independent Multicast-Sparse Mode (PIM-SM), Protocol Independent Multicast-Dense Mode (PIM-DM), etc., and establishes a multicast forwarding table for determining forwarding of an input packet through communication with an adjacent router or terminal. At this point, a multicast IP packet has a destination IP address of 224.0.0.0˜239.255.255.255, which is a class D IP address.
A procedure for processing an input multicast IP packet will be described. When a destination IP address of an input packet is a well-known multicast address assigned by Internet Assigned Numbers Authority (IANA), the input packet should be processed by a controller, and so is not forwarded and delivered to the controller. For the other multicast packets, a multicast forwarding table is explored. When a corresponding entry exists on the table, a multicast packet is forwarded to a corresponding output port. When the corresponding entry does not exist on the table, a multicast packet is destroyed or delivered to the controller so that the multicast packet is processed by upper multicast protocols.
As described above, an Ethernet-based network equipment that constitutes the Internet is classified into a switch and a router depending on a function performed by each equipment. However, a technology develops recently, a demand for providing two functions in one system increases. In this trend, by having a low-priced switch equipment perform a routing function, a user may purchase only a switch equipment that can perform a routing function instead of purchasing both a switch and a router in order to receive Internet service. Such a switch equipment that can perform a routing function can provide a great advance in an aspect of price.
On the other hand, in a current trend where communication and broadcasting are merged, a demand for viewing broadcasting through the Internet is added. For this purpose, a multicast-related function has emerged as an important issue in a network equipment. Therefore, a switch equipment that can perform a routing function requires efficient layer-2 and layer-3 multicast packet processing functions.